In Defense of Aliens

Building on last week’s article on defining invasive and alien species as well as the work of Professor Mark Davis, I am going to do the unimaginable for an ecologist and argue that maybe alien species aren’t always a bad thing. I want to emphasize that maintaining biodiversity is essential, but maybe we should focus on the role of species in their environment rather than their place of origin.

When are alien species important?

The rhetoric surrounding invasive species has led to somewhat of a native-vs-alien dichotomy in many fields of ecology, which has sometimes bled over to the public sphere. Yet the term ‘alien’ should not have negative connotations. Don’t be the little girl screaming at ET.

Alien species such as the ring-necked pheasant in South Dakota have become state symbols. Other alien species are lauded for being seen as charismatic (or ‘cute’) such as the grey squirrel in England (read to see how tortured volunteers are about killing squirrels) or important economically such as the Red King Crab in Norway. Also, those plants in your office – they’re probably aliens too and don’t you just love how they bring the room together? It’s important to remember that not all alien species are invaders, and are not necessarily unwelcome.

The Ring-Necked Pheasant has become South Dakota’s state symbol, despite being introduced just over a century ago (Image Credit: Sean McCready, CC BY-ND 2.0)

But the invaders, we have to wipe them out, right?

In the UK, assessments of programs for the control of alien species show that once a problematic species becomes established, efforts to remove the species are often ineffective. Instead of demolishing whole landscapes with pesticides, it is far more effective to implement a control program before an invasive becomes established. Taking efforts to ensure cohabitation will often be less disruptive than seeking to wipe out the invaders. And if we can’t ensure survival of the local natives, the cost of disrupting an entire ecosystem might be higher than any cost of having an invader establish itself.

Davis states that we should focus on the role species play in an ecosystem rather than where they were originally found, and I agree. Ecosystems are changing – that’s a fact, and climate change is going to change the composition of species in those ecosystems (another fact, you backwards climate change deniers). We should instead perhaps focus on maintaining biodiversity instead of stifling it to preserve the landscapes we remember, and try to focus on stopping aliens that could become invasive from becoming established.

Sam will be interviewing Mark Davis in the coming weeks. We look forward to sharing the interview with you.